In Yu-Gi-Oh!, we have a thing us fans and players like to call "retrained" monsters.
They are classic monsters from the oldest, outdated series of cards that are usually
Normal Monsters or ones with effects that would be considered weak or worthless in
the modern gameplay, and re-released with updated artwork, effects, and/or stats.
Usually they are given a name that references the old version of the monster while
still making them uniquely identified so it doesn't interfere with the rule of three.
Oftentimes this has the result of turning what used to be a single card into an archetype.

Probably one of the oldest is Celtic Guardian and it's retrained version Obnoxious Celtic Guard.
Blue-Eyes White Dragon has Blue-Eyes Alternate White Dragon and Blue-Eyes Chaos MAX Dragon and the like.
Gaia the Fierce Knight has a cacophony of retrained versions, from Swift Gaia the Fierce Knight through Gaiasaber, the Virtual Knight.
Black Luster Soldier has four, including Black Luster Soldier - Super Soldier.
Kuriboh has about a billion versions of it, it's current incarnation being Linkuriboh, a Link-1 monster.

You get it, what's old is whats new again, and if I named everything that's been retrained, we'd be here literally forever.

The real purpose of this thread is to wonder what YOU would like to see a retrained version of.
Preferably something that's a Normal Monster or non-Effect Monster.
If there's an Effect Monster who's effect is outdated, slow, useless, and could use some modernizing, maybe talk about that.
Something, hopefully, that hasn't already been retrained.

Personally I'd like to see a retrained Serpent Night Dragon.
Some refreshed artwork, some better stats, a nice effect, and maybe some "Serpent Night" archetype it can be the boss of.
I'd love it.
Or, heck, even give it the "Metaphys" treatment and make a silvery-white Wyrm version of it.
Metaphys Night Dragon could be wicked.

Keeping with Rex here why not a twin headed king rex maybe something that plays with the two head aspect maybe just like 2 attacks per turn or pop two monsters by paying life points or something like that

Keeping with Rex here why not a twin headed king rex maybe something that plays with the two head aspect maybe just like 2 attacks per turn or pop two monsters by paying life points or something like that

With Dinosaurs being popular currently, now would be a good time for it.

Oooh what about mask beast. Keep it a ritual but give it an effect like once per turn place a mask counter on an oponets monster (max 1) that monster can’t attack and it’s effect’s are negated. Remove 3 mask counters from anywhere on the field and destroy one spell/trap card.

Honestly many whole archetypes could use this treatment. I would say dark scorpion archtype would a great choice. Crystal beasts need just a few of their cards modernized to make them useful.
Single monsters I would say genex controller. The gene idea seemed cool not good enough in even causal video game use

Oooh what about mask beast. Keep it a ritual but give it an effect like once per turn place a mask counter on an oponets monster (max 1) that monster can’t attack and it’s effect’s are negated. Remove 3 mask counters from anywhere on the field and destroy one spell/trap card.

That sounds neat, like an actual "Curse" of The Masked Beast, although I feel like it might be more interesting seeing it in the anime than the game.
Counters don't tend to do well in the actual game aside from Spell Counters, and only because those are so common.
After that maybe Cloud Counters and A-Counters for Cloudians and Aliens respectively.
After that... most counters make little to no impact.
A good example are Ice Counters.

Honestly many whole archetypes could use this treatment. I would say dark scorpion archtype would a great choice. Crystal beasts need just a few of their cards modernized to make them useful.
Single monsters I would say genex controller. The gene idea seemed cool not good enough in even causal video game use

I wouldn't do a whole archetype, that wold just feel like Konami running out of ideas.
I prefer the system where an old archetype gets less than a handful of new cards that totally revitalize it.
If you could add like 1 new Crystal Beast, something to make Rainbow Dragon faster to come out and better,
and maybe a newSpell/Trap support or something, that could fix them.

As for Genex Controller... wasn't he really good and important when Genex was a thing, or wasn't he good in some other decks ouside
a straight up Genex build?
I could have sworn he was a good Tuner for something, and being a Normal Monster helped.
Machinas? I forget now, but he was good and it partly because he was a Normal Monster.
Plus, again, he's part of an archetype, so it's not like he's unsupported.

In my head, the kind of monster that needs to be retrained is one that has no effects to make it useful and doesn't already exist within an archetype for direct support.

Masked Beast would be fun - create some mechanic where the spell/trap masks equip to monsters for additional effects.
Like, off the top of my head, summon 'Faceless Fiend' DARK 4 Fiend/Effect: You cannot normal summon or set this monster. You can special summon this card (from your hand) if you control a face up "Mask of" Spell or Trap Card. This card gains the following effects for each face up "Mask of" card in your spell/trap zone.
- Mask of dispel - gain 500 LP during your standby phase
- Mask of Accursed - gain 500 LP during your standby Phase
- Mask of Brutality - either dont pay LP if it's attached to your monster or negate the +1000 if its on the opponets
- Weakness - this card gains 700 atk
- restrict - you can tribute cards
ATK 1300 DEF 1900

Great Moth would be better if you cut out all the middle Moths, make new PUG Moth able to be Summoned from hand, deck, or Graveyard as part of Cocoon of Evolution's effect, and make Cocoon of Evolution better by protecting Petit Moth from attacks, destruction, or targeting effects.
So then you'd have a retrained PUG Moth AND retrained Cocoon of Evolution, and maybe a support Spell to help evolve your Moth faster.
Or, heck, just make Cocoon of Evolution a Tuner that cannot be used as a Synchro Material monster except to Summon the retrained PUG Moth Synchro monster.
PUG Moth is so easily fixable, if Konami really cared about Insects, they'd fix it.
Yeah, yeah, Krawlers... Konami throwing a random Insect archetype here and there doesn't mean they care.

As for the "Mask of" monster support for The Masked Beast, maybe the Level 4 and lowers each represent a single "Mask of" Spell/Trap, and The Masked Beast Ritual Monster gains effects for all of them. Something like "This monster gains the following effects depending on how many "Mask of" Spells and Traps you control; 1+: blah blah blah, 2+: blah blah blah..." etc.

That level 6 synchro/rank 3 enchanting fitting room deck but he is a center of a deck that doesn't do anything well.
I think he needs to alter the attribute and level of other Genes monsters to make him useful to his own archetype.

Junk Warrior I think is kind of the last major Anime monster that has not had a major redesign or support. kind of weird with how often it was used in the Anime.